#include<iostream>
#include<stdio.h>
using namespace std;
#include <iomanip>

#include  <cmath>
int main()
{
    int a = 0, d;
    cin >> a;
    int i = 0;
    float c = 0;
    for (i = 1; i <= a; i++)
    {
        d = 1;
        if (i % 2 == 0)
        {
            d *= -1;
        }
        c += (d*((float)1 / i));







    }cout << c;


}